To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’. The 5G communication system is considered to be implemented in higher frequency (mm Wave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems. In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving to the Internet of Things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of the IoT technology and the Big Data processing technology through connection with a cloud server, has emerged. As technology elements, such as “sensing technology”, “wired/wireless communication and network infrastructure”, “service interface technology”, and “Security technology” have been demanded for IoT implementation, a sensor network, a Machine-to-Machine (M2M) communication, Machine Type Communication (MTC), and so forth have been recently researched. Such an IoT environment may provide intelligent Internet technology services that create a new value to human life by collecting and analyzing data generated among connected things. IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected cars, smart grid, health care, smart appliances and advanced medical services through convergence and combination between existing Information Technology (IT) and various industrial applications.
In line with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as a sensor network, Machine Type Communication (MTC), and Machine-to-Machine (M2M) communication may be implemented by beamforming, MIMO, and array antennas. Application of a cloud Radio Access Network (RAN) as the above-described Big Data processing technology may also be considered to be as an example of convergence between the 5G technology and the IoT technology.
The mobile communication system has evolved to a high-speed, high-quality wireless packet data communication system capable of providing data and multimedia services beyond the early voice-oriented services. The standardization organizations such as the 3rd Generation Partnership Project (3GPP), the 3rd Generation Partnership Project-2 (3GPP2), and the Institute of Electrical and Electronics Engineers (IEEE) have standardized 3rd Generation mobile communication systems based on multicarrier multiple-access scheme.
Recently, various multicarrier-based mobile communication standards such as 3GPP Long Term Evolution (LTE), 3GPP2 Ultra Mobile Broadband (UMB), and IEEE 802.16m have been developed to meet the requirements of the high-speed, high-quality wireless packet data communication services.
The existing 3G wireless packet data communication systems such as LTE, UMB, and 802.16m operate based on multicarrier multiple access schemes and adopts various techniques such as MIMO, beamforming, Adaptive Modulation and Coding (AMC), and Channel-Sensitive Scheduling to improve the transmission efficiency.
The above techniques are capable of improving transmission efficiency and system throughput in such a way of adjusting data rate by concentrating transmission power to certain antennas according to the channel quality and transmitting data selectively to the user with a high channel quality. Since most of these techniques operate based on the CSI between a base station (BS) (hereinafter, interchangeably referred to as evolved Node B (eNB) and terminals (hereinafter, interchangeably referred to as User Equipment (UE) or Mobile Station (MS)), it is necessary for the base station or the terminal to measure the channel state therebetween using a reference signal such as Channel State Indication Reference Signal (CSI-RS).
The eNB is a transmitter in downlink and a receiver in uplink and capable of managing a plurality cells for communication. A mobile communication system is made up of a plurality of eNBs distributed geographically, and each eNB manages a plurality of cells to provide the UEs with communication service.
Existing 3G and 4G mobile communication systems represented by LTE/LTE-A adopt MIMO technique which uses a plurality transmission/receive antennas to increase data rate and system throughput. The MIMO technique makes it possible to transmit spatially-separated multiple information streams. This technique of transmitting multiple spatially-separated information streams is referred to as spatial multiplexing. Typically, the number of spatially-multiplexed information streams is determined depending on the numbers of transmit and receive antennas. The number of spatially-multiplexed information streams is referred to as rank of the corresponding transmission. The LTE/LTE-A Release 11 supports 8×8 MIMO spatial multiplexing and up to rank 8.